History of EVP

One of the world's most respected scientists, Thomas Alva Edison, believed that it would one day be possible to build a machine that would help humans communicate with the dead. He once said:
If our personality survives, then it is strictly logical or scientific to assume that it retains memory, intellect, other faculties, and knowledge that we acquire on this Earth. Therefore ... if we can evolve an instrument so delicate as to be affected by our personality as it survives in the next life, such an instrument, when made available, ought to record something.
Unfortunately, Edison did not live to see his invention take shape.
In 1949, Marcello Bacci of Italy began recording voices with an old tube radio. People would come to Bacci's home to talk with their departed relatives. A few years later, two Italian priests named Father Ernetti and Father Gemelli were trying to record a Gregorian chant on their magnetophone, but the machine kept breaking. Exasperated, Father Gemelli looked up and asked his father for help. To his surprise, his dead father's voice answered from the magnetophone, "Of course I shall help you. I'm always with you."

http://science.howstuffworks.com/science-vs-myth/afterlife/evp5.htm